The GDP Model 2267B Diversity Combiner Best Source Selector houses up to sixteen high-performance synchronizer modules. Each channel can be used as a normal Bit Synchronizer and/or selected as a source for Diversity Combining (Best Source Selection). The optimized digital design of this unit affords the highest performance characteristics currently available. The unit operates to 40Mbps (20Mbps Standard, 40Mbps optional).
The standard IRIG randomizer/derandomizer for both forward and reverse sequences is provided. This unit is capable of accepting the Encapsulated data stream produced by GDP Encapsulating Bit Synchronizers such as the model2265EC.
Best Source Selection of Non-Encrypted and Encrypted Data is based on Signal Quality
GDP’s Correlating Best Source Selector is an advanced, next generation implementation of best source selection based on signal/data quality. Since signal quality is used in the decision making process, the unit does not need to see a frame synchronization pattern; therefore, the data can be encrypted. Remotely located GDP Bit Synchronizer Encapsulators provide signal quality information within the Encapsulated data stream, which is used in the best source decision process. The selected best source is accomplished seamlessly at the bit level.
The unit can be divided into three major sections, Bit Synchronizer, Path Alignment, Path Selection. The Synchronizers providing data and clock. Short-term data quality (signal quality of a small group of bits) and long-term data quality (signal quality over several hundred bits)information is extracted from the encapsulated data stream.All of this information is provided to the Path Alignment and Path Selection sections. The Path Alignment section consists of correlators and path delay/advancement correction. The Path Alignment section provides data, aligned in time, to the Path Selection section.
The Path Selection section uses the short-term and long-term data quality in addition to lock status to determine the best path. Depending upon the number of valid sources, bit-by-bit output values are selected by Majority Voting weighted by signal quality. Error correction results in up to 4 dB link performance improvement.